1. Technical Field
The present disclosure relates to a powder supply device, a developing device, and an image forming apparatus.
2. Description of Related Art
Electrophotographic image forming apparatuses are widely used. In such image forming apparatuses, an electrostatic latent image is formed on a photoreceptor that is photosensitive, the electrostatic latent image is supplied with toner particles to be developed into a toner image, and the toner image is transferred onto a recording material. Toner particles are generally supplied from a developing device to the latent image. As the toner particles are consumed in the developing device, fresh toner particles are supplied to the developing device.
Toner particles can be supplied to the developing device by, for example, 1) directly connecting a toner supply device to a toner container of the developing device; 2) directly connecting a toner supply device to a toner hopper of the developing device; 3) replacing a toner container or a toner cartridge or imaging unit equipped with the toner container, each being detachably attached to the image forming apparatus, with a new one; or 4) directly connecting a toner supply device to a toner cartridge or imaging unit. In any of the above procedures, a detector detects residual quantity of toner particles in the developing device and notifies users that the toner particles have been almost consumed in the developing device.
In the above procedures 1), 2), and 4), the toner supply device is generally configured simple and disposable. Toner particles are dropped from the toner supply device by their own weight. Such simple and disposable toner supply devices have an advantage in terms of cost because of having a small number of replaceable parts. However, dropping toner particles by their own weight may undesirably cause clogging of the discharge opening of the toner supply device. It is likely that users give the toner supply device a shake or tap when trying to remove the clogging. However, such an action may cause unexpected detachment of the discharge opening of the toner supply device from the supply opening of the developing device, resulting in the occurrence of toner leakage and scattering from the discharge opening.
Japanese Patent Application Publication No. 08-171281 describes a toner supply device which is never detachable from the developing device once being attached to the developing device. This toner supply device requires the developing device to have multiple supply openings. This toner supply device and the developing device are vertically disposed and toner particles are dropped by their own weight, which may cause toner clogging.
The above procedure 3) is simple and easy but requires a large number of replaceable parts. To reduce the number of replaceable parts to reduce manufacturing cost, there is an attempt to provide an air pump to the image forming apparatus. The air pump circulates air within the developing device to agitate or convey toner particles. Thus, there is no need to provide toner agitating members, such as screw and agitator, which results in reduction of the number of parts and manufacturing cost. However, provision of the air pump may increase the manufacturing cost or size of the image forming apparatus.